The right bright light: Silver‐exchanged zeolite 3A crystals show remarkable luminescent properties. Upon irradiation with high‐power UV light, a strong photoactivation process takes place which results in an emission increase of up to two orders of magnitude (see picture). The crystals of interest—or even small domains within one crystal—can be selectively activated by using a confocal microscope.

We have prepared two fluorescent dyes derived from 8-(4-tolyl)-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene with phenoxy and (o-bromo)phenoxy substituents at the 3,5-positions by a novel nucleophilic substitution reaction of the corresponding 3,5-dichloroBODIPY analogue. UV-vis absorption, steady-state and time-resolved fluorimetry have been used to investigate their solvent-dependent photophysical properties. The two BODIPY derivatives show narrow absorption and emission bands and display small Stokes shifts. The substituents at the 3,5-positions (phenoxy in 1 and o-bromophenoxy in 2) have a minor effect on the fluorescence quantum yields (0.16-0.40 for 1, 0.17-0.44 for 2) and lifetimes (1.09-2.51 ns for 1, 1.11-2.78 ns for 2). For both compounds, the fluorescence rate constant equals (1.5 +/- 0.1) x 10(8) s(-1).

Zeo‐Licht: Silberhaltige Zeolith‐3A‐Kristalle bestechen durch ungewöhnliche Lumineszenzeigenschaften: Die Bestrahlung mit starkem UV‐Licht führt über eine Photoaktivierung zu einer um zwei Größenordnungen intensiveren Emission (siehe Bild). Einzelne Kristalle oder kleine Bereiche davon können mithilfe eines konfokalen Mikroskops gezielt aktiviert werden.